The issue is occurring in Basics 1 - Lesson 1 (Spanish course -> "Select translation of" type of exercise)

When I click on the picture for the first time it doesn't play the audio. If I click on it again it starts working.

Btw another issue happend while I was writing this post: I pressed enter wanting to type in the next row instead it played the audio for "Soy un hombre." (in the next tab I had a lesson opened but it was at this exercise: Select translation of “the man”)

After that pressing "enter" didn't do anything so I wrote this in a text editor and copied it here. I am using firefox 28.0